Sorry

A surround sound system turns a television into a home theater. Without it, you can never approach the audio experience intended by modern-day filmmakers (or even some filmmakers from the 1950s). Sure, your HDTV can probably fake surround, but it's not going to sound like the real thing.

That real thing requires a receiver (sometimes called an amplifier), and several speakers. You can buy everything in a single package, or get the receiver separately from the speakers (you should purchase the speakers together). You'll get a better deal if you buy everything in one package, although hardcore audiophiles usually prefer to buy them separately.

Your receiver will process audio information from your DVD or Blu-ray player, as well as your DVR. You might also want it to process audio from your iPod, smartphone, tape deck, and turntable.

It must be able to send its amplified audio to at least five satellite speakers--the smallish ones that allow the sound to come from different directions--and one subwoofer. (That particular configuration is called 5.1. I discuss the alternative, 7.1, below.)

The receiver will also need multiple HDMI inputs, as well as other inputs for older technology. And it will need one HDMI output, so it can send the video information to your HDTV while rerouting the audio to your speakers.

Your receiver should also decode Blu-ray's high-quality formats, such as Dolby TrueHD and DTS-HD Master Audio.

Do you need a 7.1 system, or is 5.1 sufficient? In a 5.1 configuration, you have three front speakers near the television (left, center, and right), two surround speakers beside the audience (left and right), and a subwoofer for the low-frequency enhancement track (LFE). For 7.1, you get four surround speakers, so that you can get different sounds behind and beside you.

As I write this, few 7.1 mixes are available, but that's changing. I don't consider 7.1 absolutely essential, but if your theater room is reasonably deep, 7.1 may enhance some movies. I'm happy with 5.1, myself.

I'm not going to recommend specific models or brand names. I haven't personally tested audio equipment in a long time, and am reluctant to make recommendations. However, you'll find other people's recommendations in the original forum discussion.